Etihad Airways (EY, Abu Dhabi International) could lose access to 30 routes currently operated by equity partner Air Berlin (1991) (Berlin Tegel) under a codeshare agreement should Germany's federal aviation office (Luftfahrt-Bundesamt - LBA) decide against their pending renewal.

Quoting anonymous sources close to the negotiations, German daily, Handelsblatt, said in a report on Monday that the LBA will not likely renew the codesharing rights claiming their initial approval was granted in contravention of an existing Bilateral Air Services Agreement (BASA) between the United Arab Emirates and Germany. According to the Handelsblatt report, the routes affected are codeshare services within Europe and not Air Berlin services to Abu Dhabi.

In its defence, Air Berlin claimed on Tuesday that authorities were trying to reinterpret the provisions of the BASA during its annual review of the airlines' winter schedules. The carrier said that since the codeshare agreement began in 2012, the LBA has approved all six flight schedules.

"The Ministry of Transport is seeking to create a new interpretation of the Air Transport Agreement which fundamentally alters the provisions in respect to flights due to be operated in a few weeks," Air Berlin said in a statement to Reuters.

Air Berlin and Etihad management have held urgent talks with the German Ministry of Transport in a bid to salvage the routes, whose loss would be severe to both carriers.

Etihad's European operations, and equity acquisitions in particular, have come under close scrutiny from European regulators who are concerned about the extent to which the airline exercises control over its portfolio, which also includes Air Serbia (JU, Belgrade Nikola Tesla), Darwin Airline (Lugano), Aer Lingus (EI, Dublin International), and now, Alitalia (AZA, Rome Fiumicino).